The invention disclosed herein relates to sampling of a fluid flow which may proceed unattended for an extended period, and more particularly to a system for sampling which is proportional to either time or flow volume and which provides a predetermined sample volume of fluid which is truly representative of the actual fluid passing through the flow channel.
Flow meters in the past for use with flow sampling systems have been of the type providing questionable flow volume accuracy due to known deficiencies in the flow sensitive structure and due to clogging which occurs in impeller, orifice, or venturi type flow measurement devices. Moreover, samplers for operation in conjunction with such flow meters are subject to internal corrosion, clogging, variation in sample size and misrepresentative sample draw, which leaves subsequent analysis of samples taken as questionable means for determining the true character of the flow sampled. Samplers for use in circumstances requiring samples to be drawn per increment of time are generally not adaptable for use where samples are desired at increments of flow volume through the flow channel.
There is therefore a need for a flow and time proportional sampling system which may be used in either set of circumstances by merely pre-setting controls, or which may be operated manually if desired. Accurate and representative samples are needed for meaningful monitoring of the characteristics of the fluid flow.